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// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2018 Facebook
#include <vmlinux.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_core_read.h>
#include "bpf_tracing_net.h"
#define NUM_CGROUP_LEVELS 4
__u64 cgroup_ids[NUM_CGROUP_LEVELS];
__u16 dport;
static __always_inline void log_nth_level(struct __sk_buff *skb, __u32 level)
{
/* [1] &level passed to external function that may change it, it's
* incompatible with loop unroll.
*/
cgroup_ids[level] = bpf_skb_ancestor_cgroup_id(skb, level);
}
SEC("tc")
int log_cgroup_id(struct __sk_buff *skb)
{
struct sock *sk = (void *)skb->sk;
if (!sk)
return TC_ACT_OK;
sk = bpf_core_cast(sk, struct sock);
if (sk->sk_protocol == IPPROTO_UDP && sk->sk_dport == dport) {
log_nth_level(skb, 0);
log_nth_level(skb, 1);
log_nth_level(skb, 2);
log_nth_level(skb, 3);
}
return TC_ACT_OK;
}
char _license[] SEC("license") = "GPL";
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